The invention relates to a wound filter module with a flat filter band having a draining support and spacing band wound [i.e. the filter band] around a draining, central hollow core, whose longitudinal edges are enclosed in a wound state in a sealing element as is known e.g. according to the state of the art in U.S. Pat. No. 2,647,637. In this known wound module, both front surfaces are closed by end cap and the fluid to be filtered is distributed within the spiral in a spiral direction and the draining support layer empties in the hollow central core
A filter element according to DE-GM 80 26 874; U.S. Pat. No. 3,367,504 and DE-AS 24 62 282 is similarly designed.
Wound modules are also known (U.S. Pat. No. 3,801,400) in which, instead of a flat filter band, threads of a greater or lesser thickness are wound in bobbin-like fashion around a hollow core and those threads are optionally interlaced [cross-linked] with each other by thermal action and act over the entire layer thickness as a deep filter. However, this design is too inflexible for solving the varied filtration problems in the many types of industries and in the filtration of the many different types of fluids (gas and/or liquid) and can not be readily optimized for solving these problems.
On the one hand, such wound modules have the advantage over filter elements with a folded design with pleating arranged around a cylindrical hollow core that a large deep action is present, conditioned by the thickness of the filter-active wound cylinder, which action results e.g. in a desired design of an automatically filter-active filter cake and in higher contact times.
On the other hand, traditional wound modules have the disadvantage in comparison to filter elements with folded design of a considerably smaller freely accessible surface and therewith of an effectively filter-active surface.
The invention therefore has the problem of creating a wound filter module with simple means which can be better adapted as a result of its design to the many different requirements of the filtration art, especially as regards the possibility of variation, action as deep filter and freely accessible effective filter surface and the combination of specific filter layers.
The invention solves this problem in that the filter band and the spacing band are connected, resting on one another in a coinciding manner, by their two ends to an endless band which encloses a central hollow core or a filter core with its inner side and which is wound around the latter in a spiral manner.
Every further endless filter band with spacing band encloses the particular previously-formed filter band and is wound around the latter. In this manner, very different types of filter materials can be optimally arranged within a total filter element and the surfaces coordinated with each other in order to be able to achieve a optimum total design for the many different types of filtration problems. By virtue of this special design, the flow can pass through the filter element both transversally and also tangentially, i.e. in a spiral direction. This makes it possible, especially in the beverage industry, to handle large amounts of fluid and to achieve long dwell times.